Unmanned aerial vehicles (UAVs), also known as remotely operated aircraft, are used for many different military and commercial applications. These applications include reconnaissance, surveillance and security; communication relay; area mapping; monitoring erosion and environmental changes; agricultural, farming and commercial fishing purposes; fire detection and damage assessment; surveillance of borders, harbors and canals; convoy, road and population protection; and natural resources and wildlife management.
Some UAVs are launched using pneumatic tube launchers to eliminate the need for long runways. UAVs may fly autonomously along a preprogrammed flight path that is modifiable from a ground control station while in flight. It is common to use Differential GPS to provide enhanced accuracy for ensuring that the UAV flies to within inches of the desired location for recovery.
One of the problems with UAVs is how to successfully, that is with no or minimal damage to the aircraft, recover or capture them at the end of a flight if a runway or a runway-like surface, such as a road, is not available. This is a significant problem when the UAV is to land on a boat or ship, such as a helicopter landing pad on a ship. It is also problem in remote or otherwise unimproved areas in the field. Several different recovery systems have been developed to recover the UAV without destroying it. One is to use a horizontal line and a hook on the UAV similar to that used on aircraft carriers with piloted aircraft. Another system uses nets to capture the UAV. Another system, described in U.S. Pat. No. 7,059,564, uses a vertically extending recovery line; a wing of the UAV hits the recovery line which catches the tip of the wing and spins the UAV around until it comes to rest.